German Patent Application No. DE 10 2006 057 247 relates to a supercharging device in which thermal energy is extracted from the exhaust gas of an internal combustion engine via a steam circuit and is partially converted into mechanical and electrical energy via a turbine. Unused waste heat is dissipated into the environment via a separate condenser. A supercharging device is used in particular to charge an internal combustion engine. At least one exhaust-gas heat exchanger of a circuit for a working medium is located in an exhaust system. Upstream from the at least one exhaust gas heat exchanger is a supply unit in the circuit of the working medium. The working medium circuit contains at least one expansion machine via which at least one compressor part situated in the intake system of the internal combustion engine is driven.
An article entitled “BMW four-cylinder engine uses waste heat to increase performance—engine with turbine” is known from the magazine “Auto, Motor and Sport”, volume 10, page 26/2005. According to this publication, an internal combustion engine converts approximately two-thirds of the energy in the fuel into waste heat that is either absorbed by the cooling system of the internal combustion engine or is removed via the exhaust system of the internal combustion engine. The previously unused waste heat may be used to increase efficiency by up to 15% in internal combustion engines. For this purpose, a 1.8-liter four-cylinder engine is coupled to a two-stage steam turbine which acts on the crankshaft of the 1.8-liter four-cylinder engine. Hot steam is generated by heat exchangers in the vicinity of the exhaust pipe in the exhaust system of the internal combustion engine. With the aid of a water circuit, cooling fluid may be branched off of the cooling circuit of the internal combustion engine. As a result of the driving of the crankshaft via the two-stage steam turbine, the output and the torque of the internal combustion engine may be increased or the specific fuel consumption may be significantly lowered.